devmap_dup(9E)							Driver Entry Points						    devmap_dup(9E)

NAME

       devmap_dup - device mapping duplication entry point

SYNOPSIS

       #include <sys/ddi.h>
       #include <sys/sunddi.h

	int prefixdevmap_dup(devmap_cookie_t dhp, void *pvtp, devmap_cookie_t new_dhp, void **new_pvtp);

INTERFACE LEVEL

       Solaris DDI specific (Solaris DDI).

ARGUMENTS

       dhp	       An opaque mapping handle that the system uses to describe the mapping currently being duplicated.

       pvtp	       Driver private mapping data for the mapping currently being duplicated.

       new_dhp	       An opaque data structure that the system uses to describe the duplicated device mapping.

       new_pvtp        A pointer to be filled in by device drivers with the driver private mapping data for the duplicated device mapping.

DESCRIPTION

       The  system  calls  devmap_dup()  when a device mapping is duplicated, such as during the execution of the fork(2) system call.	The system
       expects devmap_dup() to generate new driver private data for the new mapping, and to set new_pvtp to point to it. new_dhp is the handle	of
       the new mapped object.

       A non-zero return value from  devmap_dup() will cause a corresponding operation such as fork() to fail.

RETURN VALUES

       devmap_dup() returns the following values:

       0	       Successful completion.

       Non-zero        An error occurred.

EXAMPLES

       static int
       xxdevmap_dup(devmap_cookie_t dhp, void *pvtp, devmap_cookie_t new_dhp,
	   void **new_pvtp)
       {
	   struct xxpvtdata    *prvtdata;
	   struct xxpvtdata    *p = (struct xxpvtdata *)pvtp;
	   struct xx_softc     *softc = p->softc;
	   mutex_enter(&softc->mutex);
	   /* Allocate a new private data structure */
	   prvtdata = kmem_alloc(sizeof (struct xxpvtdata), KM_SLEEP);
	   /* Return the new data */
	   prvtdata->off = p->off;
	   prvtdata->len = p->len;
	   prvtdata->ctx = p->ctx;
	   prvtdata->dhp = new_dhp;
	   prvtdata->softc = p->softc;
	   *new_pvtp = prvtdata;
	   mutex_exit(&softc->mutex);
	   return(0);
       }

SEE ALSO

       fork(2), devmap_callback_ctl(9S)

       Writing Device Drivers

SunOS 5.10							    21 Jan 1997 						    devmap_dup(9E)